Rembrandt created his distinctive portraits with a small palette of colors dominated by dark earth tones and golden highlights. He was a master of chiaroscuro, an Italian term for a style using strong lights and heavy shadows to create depth in a painting and a center of interest. Rembrandt used it to emphasize the faces and hands in his portraits; what his subjects were wearing and their setting are of less importance, melding into a dark background.
A modern version of Rembrandt’s palette should include all these colors: yellow ocher, burnt sienna, burnt umber, white, black, and a brownish or orangey red such as cadmium red deep. "Break" the colors by mixing them—Rembrandt was known for his complex mixtures rather than raw color (our equivalent of straight from the tube). To get a bluish gray, he’d mix ground charcoal into white paint. Rembrandt worked on a colored ground, never white. He used mostly a gray or grayish brown; these got darker as he got older.
Rembrandt worked on wood panels and canvas. His historic method includes hints on how to reproduce the colored ground which underlay his rich dark paintings.
"The first layer of primer for the panels is glue-chalk gesso, which was sanded to smooth out the irregularities of the panel's surface, then a layer of white lead in linseed oil, with a small amount of Umber added, probably to speed drying, covered with a transparent brown imprimatura, which creates the golden glow characteristic of his work. Most of his canvases are primed with a double ground, the first layer of which is a red-orange ochre, perhaps to fill the texture of the canvas, then overlaid with a light, warm grey made from lootwit (lead white with chalk, ground in linseed oil), charcoal, Raw Umber, and various other earth colors."
Rembrandt may have been restrained in his choice of colors, but there was nothing restrained about the impasto way he applied them, particularly later in his career.
Early in his career he began building up the opaque passages in his lights more heavily, and texturing them to take on the physical convolutions of the lighted surfaces of his subjects, most notably the skin textures of male subjects, including himself. Exactly how he created this texture is unknown. It can be duplicated or approximated by building up a somewhat thick layer of opaque paint, then passing a soft brush over the surface while it is still wet. It seems Rembrandt began to superimpose glazes of red over these textured passages when dry, then wipe them off with a rag, leaving traces remaining in the low spots to create an even more convincing texture of rough flesh.
The Dutch artist Arnold Houbraken, who was a pupil of a pupil on Rembrandt's commented on the thickness with which he lay colors saying that his colors were “so heavily loaded that you could lift it from the floor by its nose.” Rembrandt developed his paintings on the canvas, moving around paint even when it was very thick. The effect you’re after is called sprezzatura, or “apparent carelessness”. How deceptively simple Rembrandt makes it look!
Eliot, Virgil. "The Technical Innovations of Rembrandt." ARC Art Renewal Center.